Is this an Art Deco era necklace?

[minarima1]

Hi all,

I recently purchased this necklace on the off chance it's genuinely from the Art Deco period. Is anyone able to tell me more about it? It doesn't appear to have any inscriptions nor hallmarks, however I've tested the chain and it tested positve for sterling silver, and its total length is 36 inches-

[gauntlettgems]

Just curious, what made you think Art Deco? Give a better pic of the clasp, please.

[minarima1]

I was thinking possible 1920s mainly because of the materials used, the style, and the fact that the clasp isn't hallmarked in any way: